LU-7993 test: Fix division by 0 in info prints

LU-7993 test: Fix division by 0 in info prints

Some of the information only prints in sanity/116a don't account for a
0 in the minimum number and thus divide by zero, but only print if MIN
is above zero, so this just doesn't do the calculation if it isn't
needed.

Signed-off-by: Nathaniel Clark <nathaniel.l.clark@intel.com>
Change-Id: I7003739f6b518f981a1058d41b19bca258e1d11e
Reviewed-on: http://review.whamcloud.com/19359
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>